When concrete elevator cores are built on jobsites inside corners are required. Inside forms are used to form the inside of the elevator core. Once the concrete has set the inside forms must be stripped inside the elevator core. Typically, to strip the inside form, provisions must be made to forcibly decrease the perimeter of the form to break the form from the concrete and strip the form. This is necessary in order to reuse the form at the next elevation of forming to pour another course of concrete on top of the previously poured course. A self-lifting form, such as described in U.S. Pat. Nos. 9,611,663; 9,279,260 and/or 8,020,271 is used to move the inside form up the elevator core. These patents are herein incorporated by reference. In this way, the elevator core is cast course-by-course from a lowest elevation to a highest elevation, to complete the elevator core for the building.
One of the present design inside corners for self-lifting forms involves the use of a steel inside corner approximately 7″×7″. This inside corner is bolted to the adjacent form panel with an approximately ½″ thick rubber spacer. In order to strip this corner there are plates welded to the steel channel walers that meet at the inside corner.
These plates have two sets of holes through them, one set that overlaps (i.e., not precisely aligned or registered) and another set that is aligned. In order for the corner to strip away from the formed concrete, a tapered pin is driven out of the aligned set of holes and into the overlapping holes. This causes the overlapping holes to come into alignment. When the overlapping holes are aligned, the steel corner is caused to bend and flex. The rubber spacer also compresses on one edge. This causes the corner to collapse enough to allow the corner form to strip and the formwork to be raised.
In order to strip and reset the present design corner, a workman with a large hammer must climb up the formwork. The formwork may be as high as 18 feet. There are up to four different locations, at different elevations, where the driving of pins must be done in each corner. Once tied off at a location the workman must drive out a pin that is in the aligned position hole and re-drive the pin into the overlapping holes. Once this is done at all the corner locations the form can be raised. Once the form is raised to the next course, the workman once again must climb the formwork at all the pinning locations, drive the pin out of the overlapping hole or stripped position and then re-drive the pin into the aligned holes corresponding to the set position for forming and pouring concrete.
The present inventor has recognized that this must occur at all the pinning locations in all the corners. This involves significant climbing and work by workmen, and cost, to accomplish the task.